This invention concerns the grinding of crank pins, especially an improved process of finish grinding such components particularly crankpins of steel crankshafts using a computer controlled grinding machine.
For finish grinding the depth of stock to be removed is normally less than 0.5 mm on radius.
Crank pins are traditionally ground using a continuous feed method in which the rotating grinding wheel is fed into the workpiece by advancing the wheelhead, as the workpiece is rotated. The rate of wheel advance is usually decreased as the workpiece approaches finish size, once to size, sparkout using wheel dwell is performed. This normally consists of a few turns of the workpiece whilst the wheelhead (on which the rotating grinding wheel is carried) remains fixed in position relative to the workpiece, with the wheel just grazing the pin.
During the rest of the process, the wheelhead is advanced and retracted under computer control so as to maintain contact between wheel and crankpin as the latter is rotated around the crankshaft axis. The crankshaft is driven by a headstock drive.